ios-swiftui

Purpose

This skill provides expertise in SwiftUI for building declarative UIs in iOS apps, focusing on views, state management, animations, and navigation to streamline development.

When to Use

Use this skill for iOS projects requiring responsive interfaces, such as apps with dynamic content, user interactions, or complex navigation; ideal for new iOS apps (iOS 13+), prototyping, or migrating from UIKit.

Key Capabilities

• Create and modify views using structs that conform to the View protocol.
• Manage state with @State for local changes, @Binding for parent-child communication, @ObservedObject for external models, and @EnvironmentObject for app-wide data.
• Implement animations via withAnimation{} and modifiers like .animation(.easeIn).
• Handle navigation with NavigationStack, including stacks, lists, and sheets for multi-screen flows.

Usage Patterns

To build a SwiftUI view, define a struct conforming to View and use modifiers in the body; for state, wrap variables with @State and update via functions. Pattern: Use @EnvironmentObject for shared data by injecting via .environmentObject() in the app's root view. For lists, apply List{} with ForEach{} for dynamic content. Always preview views with #Preview{} for rapid iteration. To handle sheets, use .sheet(isPresented: $isShowing) {} on a View.

Common Commands/API

Use @State for local state: @State private var count: Int = 0 then increment with Button("Tap") { count += 1 }. Apply modifiers like .padding() or .foregroundColor(.blue) directly on views, e.g., Text("Hello").padding().background(.yellow). For animations, wrap changes: withAnimation { self.isAnimating.toggle() } on a view with .animation(.default). Navigation example: NavigationStack { List(items, id: \.id) { item in NavigationLink { DetailView(item: item) } } }. Config format: In Xcode, ensure SwiftUI is selected in project settings; import SwiftUI in files.

Integration Notes

Integrate SwiftUI into an existing iOS project by adding a SwiftUI view to a UIKit app via UIHostingController; set up in code like let hostingController = UIHostingController(rootView: MySwiftUIView()). For app-wide objects, pass via .environmentObject() in the @main App struct, e.g., @main struct App: App { var body: some Scene { WindowGroup { ContentView().environmentObject(MyModel()) } } }. If API keys are needed (e.g., for networking), load from env vars like let apiKey = ProcessInfo.processInfo.environment["MY_API_KEY"] and handle in your observed objects. Ensure iOS deployment target is 13.0+ in Xcode project settings.

Error Handling

Handle state-related errors by ensuring @State updates occur on the main thread; use DispatchQueue.main.async for async updates, e.g., DispatchQueue.main.async { self.data = newData }. For navigation issues, check NavigationStack paths and use .onAppear{} to validate state, e.g., onAppear { if path.isEmpty { path.append("home") } }. Common errors: "Cannot use instance member" – fix by making variables @State; log errors with print() or os_log for debugging. If bindings fail, verify the wrapped value is correctly passed, e.g., in child views.

Concrete Usage Examples

Example 1: Simple counter view – Create a view with @State: struct CounterView: View { @State var count: Int = 0 var body: some View { VStack { Text("Count: \(count)") Button("Increment") { count += 1 } } } }. Use in app: ContentView().environment(\.colorScheme, .dark). Example 2: Navigation with list – Build a list view: struct ItemList: View { @State var items = [1,2,3] var body: some View { NavigationStack { List(items, id: \.self) { item in Text("Item \(item)") } .navigationTitle("Items") } } }. Integrate by presenting: ItemList().sheet(isPresented: $showSheet) { DetailView() }.

Graph Relationships

• Related to cluster: mobile (e.g., shares dependencies with android-kotlin skill).
• Links to: swift (for core language features), ios-core (for foundational iOS APIs).
• Dependencies: Requires xcode-tools for building; integrates with firebase-ios for backend services.